Question

1. There is a seal mark on the piece of paper,for I pressed the seal on the piece of paper.

2. There is a seal on the piece of paper,for I pressed the seal on the piece of paper.

(Which one is correct? Do I have to use seal or seal mark about the mark of the paper?)

Answer 1

The second is better than the first. You don't need to use the word "mark."
(And don't forget to put a space after the comma!)